title: Pressure-induced phase transitions and correlation between structure and superconductivity in iron-based superconductor Ce(O(0.84)F(0.16))FeAs.
abstract: High-pressure angle-dispersive X-ray diffraction experiments on iron-based superconductor Ce(O(0.84)F(0.16))FeAs were performed up to 54.9 GPa at room temperature. A tetragonal to tetragonal isostructural phase transition starts at about 13.9 GPa, and a new high-pressure phase has been found above 33.8 GPa. At pressures above 19.9 GPa, Ce(O(0.84)F(0.16))FeAs completely transforms to a high-pressure tetragonal phase, which remains in the same tetragonal structure with a larger a-axis and smaller c-axis than those of the low-pressure tetragonal phase. The structure analysis shows a discontinuity in the pressure dependences of the Fe-As and Ce-(O, F) bond distances, as well as the As-Fe-As and Ce-(O, F)-Ce bond angles in the transition region, which correlates with the change in T(c) of this compound upon compression. The isostructural phase transition in Ce(O(0.84)F(0.16))FeAs leads to a drastic drop in the superconducting transition temperature T(c) and restricts the superconductivity at low temperature. For the 1111-type iron-based superconductors, the structure evolution and following superconductivity changes under compression are related to the radius of lanthanide cations in the charge reservoir layer.
authors.affiliation: Natural Science Research Center, Academy of Fundamental and Interdisciplinary Sciences, Harbin Institute of Technology, Harbin 150080, China. zhaojinggeng@gmail.com
authors.forename: Jinggeng
authors.initials: J
authors.lastname: Zhao
authors.forename: Haozhe
authors.initials: H
authors.lastname: Liu
authors.forename: Lars
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authors.lastname: Ehm
authors.forename: Dawei
authors.initials: D
authors.lastname: Dong
authors.forename: Zhiqiang
authors.initials: Z
authors.lastname: Chen
authors.forename: Qingqing
authors.initials: Q
authors.lastname: Liu
authors.forename: Wanzheng
authors.initials: W
authors.lastname: Hu
authors.forename: Nanlin
authors.initials: N
authors.lastname: Wang
authors.forename: Changqing
authors.initials: C
authors.lastname: Jin